Separation of phenols



Patented Feb. 2l, 1950 SEPARATION OF PHENOLS -HoraceAndrew Basterield, Norten-on-.Teea England, assignor v to Imperial .Chemical IndustriesLimited, a corporation .of'lGreatBritain fNo Drawing. Application 'June19, $119.45, Seria'l No.600\,40'6. In Great Britain. June *19; .19.44

.ill'iisirwention vrelates .to the production. and separation-.ofmhenols.

1I ,have found `that2.2.4i;dimethyl, G-tertiany loutyl,y phenol. canheseparate-dv `frommixtures containing vit. and .2:5-dimethyl,.ll-tertiary `butyl phenol by .treating :the mixture. with an aqueoussolution. .of .,a .hydroxide Yof. an alkali-metal yand separating from.the mixture 4fthe insoluble 2:4- dimeth-ylf, 6-tertianyfloutylqchenol.`

In fthe .preparation of .:dimethyl butyl phenols by the fbutylation of,a mixture containing 2 :A- dimet-llyl phenol anol` 2 :ii-dimethyl`phenol` preferential fbntylation Yof the 25a-dimethyl `phenol occurs.When.butylating1` .ith .isobutene -a Vgiven mixture "of :these 'dimethylphenol-s, the quantity oimro'duct lwhichis insoluble yin an aqueous:solutionioffa hydroxidefof an-alkalixmetal rises to afmaximum value,and .then-decreases. This insoluble' .product -is substantially vpurer2:1if-dimethyl, -"tertary butylphenol.

V.ilss fa further feature fof fthe present invention therefore,4thereis.` `provided a vprocess 'for lthe production of 2:4-dimethyl,`.f6-*tettiary butyl nhenolfrom. mixtures containing VBill-.dimethylphenol and '.2 :15 eiiimfethyl :phenoiwhich comprises butyl'ating the:mixture to :an "extent not substaritially :greatenlthanthat at whichthere -is obtained the 4'maximum quanti-ty `of vproduct insolulile yinan laqueous solution oi a hydroxideof an falkali f'metal, -treating thef butylated `mixture With an aqueous vsolution `o'i a "hydroxide of'fa'nlalkali metal lanti separating `insoluhle"2:4di methyl, "li-tertiarybutyl nheno'l 'from 'the :aqueous alkaline solution.

The mixturefcontainingdimethyl 'p'henols may vbefbutylated byany'fconvenientmethod for lein yample;."byjtrea'ting it Wlthisobutene in:theffpres- 'ence y'of fa catalystiwhich' maybe isulphuric' laciol lorphosphoricacid The use 'of `sulphuric acid Aas 4a 'to-beendisadvanta'geous vbecause it'leads to the production, lin sidereactions, of aromatic sulphonicacds, `and esters thereof, the "latter'being particularly dilcult vto `remove "from the reaction products;.Sulphuric .acidls however, a particularly desirable catalyst because ofits activity, cheapness 'and availability, and thefprocf ess of thepresent invention enables ittobeuse satisfactorilyinf'thebutylationstep. '.Thus, during the .separation of the 21a-dimethyl,floutyl gillend, any sulphuricwacid and .sulphonic acids rontain'ednithecru-de reaction mixturefromthe 'hutylating 'step' vare neutralisedlibycaustic. .al- "all Yandv thepro'ducts of neutralisation remain dissolvedin the aqueous solution of caustic al- .40 catalyst'v'forithe`butyl-ation of phenols has hither- 2 kaliand'are thus..separatedfrom-the vdesired insoluble 2:4-dimethyl, 6huty1 phenol, .while..theesters of sulphonic'acidsare'substantially completely 4decomposed by`the .caustic alkali to .give products `which,alsoremain dissolved. inthe aqueous solution of caustic alkali.

The process of vthe .present invention falsoprovides aconvenient meansAfor the separation. of 2x4-dimethyl 1phenol .from mixtures .containingit -and 2:5dimethyl phenol .which comprises butylating .the mixture,treating athefbutylated mix-ture with yan -Iaqueous solution of .aVhydroxide of an alkali metaLsepaIatng the .insoluble2:4 dimethyl,6-.tertiary butyl `phenol and debutyl.- ating by known- .means to .give.2A-.dimethyl phenol. For example the 2:4-dimethyl,6.tertia11y butylphenol may ,bedebutylated by ,heating it with :acsmall quantity-of isulphuriczacid at va =tem p'erature-of 200 C. or higher. Preferably' themixture is hutylated to Vanextent notsubstantiallyl `greater :than that.atwhich there is rolotained the maximum quantityof ,product4insoluble-:in-an aqueous solution of a hydroxide of an alkali-metal.

.The coneentrationof rtheaqueous solutionof the hydroxideof `itheallzalimetal fmay vary within Wideilimits; I vhaveiound lit -satisfactom7 ttouseafsolutioncontaining 10% by weight.

The treatment tof 'the 'mixture containing 4dimethyl butyl phenols vwithcaustic'alkali maybe carried out lsatisfaetorilyat. vroom temperature,butitfis ,preferable `to carry .outthe treatment sat elevatedtemperature, fior example at 20 C. .to 409 C.

While the separated 2x4-dimethyl, 6-buty1 phenoks reasonably pure, :it:may be further' treat- .ed .fior example, by .steam- -distillation, ,inorder ito obtain 1 sa product. havin-g -a fbetter colour and iahigherfd'egreeef purity.

Itshould be understood that y.the .residual'raqueous :alkaline solutionobtained `according to the present inventionmay also be .treatedbyknown:ricains-fori'` themecovery ofthe-.phenols it contains.

Example k comprises the steps of butylating 6-buty1 phenol and 15%2:5-dimethyl, 4-butyl phenol, these figures representing 33% ofunreacted phenols, 54% of 2:4-dimethyl phenol converted to 2:4-dimethyl,G-butyl phenol and 13% of 2 5-dimethyl phenol converted to 2:5-dimethyl,i-butyl phenol. This mixture was treated with gms. of caustic sodadissolved in 200 mls. of water, whereby two layers were formed. Theinsoluble oily layer was separated and steam-distilled to givesubstantially quantitative recovery oi the 2 :4- dimethyl, 6-butylphenol formed.

I claim:

1. A process for the separation of 2:4-dimethyl, G-tertiary butyl phenolfrom mixtures containing it and 2 z -dimethyl, 4-tertiary butyl phenolwhich comprises the steps of treating the mixture with an aqueoussolution of a hydroxide of an alkali metal suflcient to dissolve the2:5-dimethyl, 4- tertiary butyl phenol and separating insoluble 2 :4-dimethyl, -tertiary butyl phenol from the aqueous liquor containing thedissolved 21S-dimethyl, 4-tertiary butyl phenol component.

2. A process for the separation of 2:4-dimethyl, G-tertiary butyl phenolfrom mixtures containing it and 2 :5-dimethyl, 4-tertiary butyl phenolwhich comprises the steps of butylating a mixture containing2z4-dimethyl phenol and 2:5-dimethyl phenol, treating the butylatedmixture containing Zvi-dimethyl, 6tertiary butyl phenol and 2:5-dimethyl, 4-tertiary butyl phenol with an aqueous solution of ahydroxide of an alkali metal sufiicient to dissolve the 2:5-dimethyl,4-tertiary butyl phenol and separating insoluble 2:4-dimethyl, 6- butylphenol from the aqueous liquor containing the dissolved 2 :5-dimethyl,4-tertiary butyl phenol component.

3. A process for the separation of 2:4-dimethyl, G-tertiary butyl phenolfrom mixtures containing it and 2 :5-dimethyl, 4-tertiary butyl phenolwhich comprises the steps of butylating a mixture containing 2:4dimethylphenol and 2:5-dimethyl phenol with isobutene, treating the butylatedmixture containing 2:4-dimethyl, G-tertiary butyl phenol and2:5-dimethyl, 4-tertiary butyl phenol with an aqueous solution of ahydroxide of an alkali metal suiiicient to dissolve the 2:5-dimethyl,li-tertiary butyl phenol and separating insoluble 2:4-dimethyl, -butylphenol from the aqueous liquor containing the dissolved 2:5-dimethyl, 4-tertiary butyl phenol component.

4. A process for the separation of 2:4-dimethyl, G-tertiary butyl phenolfrom mixtures containing it and 2 5-dimethyl, 4-tertiary butyl phenolwhich a mixture containing 2:4-dimethyl phenol and 2:5-dimethyl phenolwith isobutene in the presence of an acid selected from the groupsulphuric acid, phosphoric acid, treating the butylated mixturecontaining 2:4-dimethyl, -tertiary butyl phenol and 2:5- dimethyl,4-tertiary butyl phenol with an aqueous solution of a hydroxide of analkali metal suflicient to dissolve the 2:5-dimethyl, 4-tertiary butylphenol and separating insoluble 2:4-dimethyl, 6- butyl phenol from theaqueous liquor containing the dissolved 2:5-dimethyl, 4-tertiary butylphenol component. y

5. A process for the separation of 2:4-dimethyl, G-tertiary butyl phenolfrom mixtures containing it and 2 :Ei-dimethyl, 4-tertiary butyl phenolwhich comprises the steps of butylating at a temperature below 60 C. amixture containing 2:4-dimethyl phenol and 2:5-dimethyl phenol withisobutene in the presence of an acid selected from the group sulphuricacid, phosphoric acid, treating the butylated mixture containing2:4-dirnethyl, B-tertiary phenol and 2:5-dimethyl, 4-tertiary butylphenol with an aqueous solution of a hydroxide of an alkali metalsuii'icient to dissolve the 2:5- dimethyl, 4-tertiary butyl phenol andseparating insoluble 2:4-dimethyl, 6-butyl phenol from the aqueousliquor containing the dissolved 2:5-dimethyl, 4-tertiary butyl phenolcomponent.

6. A process for the separation of 2:4-dimethyl, 6tertiary butyl phenolfrom mixtures containing it and 2 5-dimethyl, li-tertiary butyl phenolwhich comprises the steps of butylating a mixture containing 2:4dimethylphenol and 2:5-dimethyl phenol to an extent not substantially greaterthan that at which there is obtained the maximum quantity of productinsoluble in an aqueous solution of a hydroxide of an alkali metal,treating the butylated mixture containing 2:4-dimethyl, G-tertiary butylphenol and 21E-dimethyl, 4-tertiary butyl phenol with an aqueoussolution of a. hydroxide of an alkali metal suflicient to dissolve the2:5-dimethyl, 4-tertiary butyl phenol and separating insoluble2:4-dimethyl, G-butyl phenol from the aqueous liquor containing thedissolved 2:5-dimethyl, 4-tertiary butyl phenol component.

'7. A process for the separation of Zvi-dimethyl, 6-tertiary butylphenol from mixtures containing it and 2 -dimethyl, 4-tertiary butylphenol which comprises the steps of butylating with isobutene -a mixturecontaining 2:4-dimethyl phenol and 22S-dimethyl phenol to an extent notsubstantially greater than that at which there is obtained the maximumquantity of product insoluble in an aqueous solution of a hydroxide ofan alkali metal, treating the butylated mixture containing 2:4-dimethyl, 6-tertiary butyl phenol and 2:5-dimethyl, 4-tertiary butylphenol with an aqueous solution of a hydroxide of an alkali metalsufficient to dissolve the 2:5-dimethyl, 4-tertiary butyl phenol andseparating insoluble 2:4-dimethyl, G-butyl phenol from the aqueousliquor containing the dissolved 2:5-dimethyl, il-tertiary butyl phenolcomponent.

8. A process for the separation of 2x4-dimethyl, 6tertiary butyl phenolfrom mixtures containing it and 2 5-dimethyl, 4-tertiary butyl phenolwhich comprises the steps of butylating with isobutene in the presenceof an acid selected from the group consisting of sulphuric acid,phosphoric acid, a mixture containing 2:4-dimethyl phenol and2:5-dimethyl phenol to an extent not substantially greater than that atwhich there is obtained the maximum quantity of product insoluble in anaqueous solution of a hydroxide of an alkali metal, treating thebutylated mixture containing 2:4-dimethyl, G-tertiary butyl phenol and2:5-dimethyl, 4-tertiary butyl phenol with an aqueous solution of ahydroxide of an alkali metal sufficient to dissolve the 22S-dimethyl,li-tertiary butyl phenol and separating insoluble Zvi-dimethyl, 6-butylphenol from the aqueous liquor containing the dissolved 22B-dimethyl,4tertiary butyl phenol component.

HORACE ANDREW BAS'I'ERFIELD.

REFERENCES CITED The following references are of record in the iile ofthis patent:

1. A PROCESS FOR THE SEPARATION OF 2:4-DIMETHYL, 6-TERTIARY BUTYL PHENOLFROM MIXTURES CONTAINING IT AND 2:5-DIMETHYL, 4-TERTIARY BUTYL PHENOLWHICH COMPRISES THE STEPS OF TREATING THE MIXTURE WITH AN AQUEOUSSOLUTION OF A HYDROXIDE OF AN ALKALI METAL SUFFICIENT TO DISSOLVE THE2:5-DIMETHYL, 4TERTIARY BUTYL PHENOL AND SEPARATING INSOLUBLE2:4DIMETHYL, 6-TERTIARY BUTYL PHENOL FROM THE AQUEOUS LIQUOR CONTAININGTHE DISSOLVED 2:5-DIMETHYL, 4-TERTIARY BUTYL PHENOL COMPONENT.2:5-DIMETHYL,